iOS: add global function 'isQtApplication'

Several places in the code we need to check if the plugin is
running as a cross-platform Qt application or inside a
native app. So we refactor this function to qiosglobal so
we can access it from everywhere.

Change-Id: I78db0dcde71b7d281868ce304867c8f876caef2a
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@digia.com>

src/plugins/platforms/ios/qiosglobal.h

@@ -49,6 +49,7 @@
 
 QT_BEGIN_NAMESPACE
 
+bool isQtApplication();
 CGRect toCGRect(const QRect &rect);
 QRect fromCGRect(const CGRect &rect);
 Qt::ScreenOrientation toQtScreenOrientation(UIDeviceOrientation uiDeviceOrientation);

src/plugins/platforms/ios/qiosglobal.mm

@@ -40,10 +40,23 @@
 ****************************************************************************/
 
 #include "qiosglobal.h"
+#include "qiosapplicationdelegate.h"
 #include <QtGui/qscreen.h>
 
 QT_BEGIN_NAMESPACE
 
+bool isQtApplication()
+{
+    // Returns true if the plugin is in full control of the whole application. This means
+    // that we control the application delegate and the top view controller, and can take
+    // actions that impacts all parts of the application. The opposite means that we are
+    // embedded inside a native iOS application, and should be more focused on playing along
+    // with native UIControls, and less inclined to change structures that lies outside the
+    // scope of our QWindows/UIViews.
+    static bool isQt = ([[UIApplication sharedApplication].delegate isKindOfClass:[QIOSApplicationDelegate class]]);
+    return isQt;
+}
+
 CGRect toCGRect(const QRect &rect)
 {
     return CGRectMake(rect.x(), rect.y(), rect.width(), rect.height());

src/plugins/platforms/ios/qiosscreen.mm

@@ -139,7 +139,7 @@ QIOSScreen::QIOSScreen(unsigned int screenIndex)
     const qreal millimetersPerInch = 25.4;
     m_physicalSize = QSizeF(m_geometry.size()) / unscaledDpi * millimetersPerInch;
 
-    if ([[UIApplication sharedApplication].delegate isKindOfClass:[QIOSApplicationDelegate class]]) {
+    if (isQtApplication()) {
         // When in a non-mixed environment, let QScreen follow the current interface orientation:
         UIViewController *controller = [UIApplication sharedApplication].delegate.window.rootViewController;
         setPrimaryOrientation(toQtScreenOrientation(controller.interfaceOrientation));

src/plugins/platforms/ios/qioswindow.mm

@@ -196,7 +196,7 @@ QIOSWindow::QIOSWindow(QWindow *window)
     , m_glData()
     , m_devicePixelRatio(1.0)
 {
-    if ([[UIApplication sharedApplication].delegate isKindOfClass:[QIOSApplicationDelegate class]])
+    if (isQtApplication())
         [[UIApplication sharedApplication].delegate.window.rootViewController.view addSubview:m_view];
 
     setWindowState(window->windowState());